The technology according to Patent Document 1 relates to a control device for an internal combustion engine having the above-described configuration. According to this technology, when the internal combustion engine is started up, unburned hydrocarbons (unburned HC) remaining in the combustion gas are trapped in the combustion chamber by advancing the closing timing of the valve opening/closing timing control mechanism for the exhaust valve. After the startup, an overlap period, during which both the exhaust valve and the intake valve are open, is extended by retarding the valve opening/closing timing control mechanism for the exhaust valve. Consequently, the exhaust gas that has been discharged to the exhaust passage is taken into the combustion chamber again, and the unburned HC gas contained in the exhaust gas contributes to combustion again, which leads to the reduction of emissions.
According to Patent Document 1, the valve opening/closing timing control mechanism (referred to as “valve timing control mechanism” in this document), which sets the timing of opening/closing the intake valve and the exhaust valve, is configured to be of an electromagnetic type including: a movable unit made of magnetic material; a coil for valve opening; and a coil for valve closing.
The technology according to Patent Document 2 also relates to a control device for an internal combustion engine. According to this technology, an inner rotor is provided at the tip of the camshaft, and an outer rotor, to which rotative power is transmitted from the camshaft, is fit onto the inner rotor. A fluid pressure chamber located between these rotors is partitioned by a vane into two chambers, namely an advancing chamber and a retarding chamber, and the fluid pressure chamber is configured such that the relative rotation phase of the crankshaft and the camshaft can be freely changed by supplying a fluid to either the advancing chamber or the retarding chamber.
According to Patent Document 2, in order to regulate the relative rotation phase of the inner rotor and the outer rotor, a first lock pin, which is biased by a spring, a first regulation groove, into which the first lock pin fits, a second lock pin, which is biased by a spring, and a second regulation groove, into which the second lock pin fits, are provided. Also, a configuration is adopted in which the relative rotation phase of the inner rotor and the outer rotor can be maintained to be a phase that is suited for the startup of the internal combustion engine in the state in which the first lock pin is fit into the first regulation groove and the second lock pin is fit into the second regulation groove.